Diffuse axonal injury (DAI) refers to extensive lesions in white matter tracts of the brain, and is a result of traumatic shearing or rotational forces that occur when the head is rapidly accelerated or decelerated.
Chronic traumatic encephalopathy (CTE) is a progressive degenerative disease that may develop in an individual with a history of multiple sub-concussive or concussive head injuries, or other forms of head injury having diffuse axonal injuries. CTE has been commonly found in athletes participating in American football, ice hockey, wrestling, and other contact sports who have experienced repetitive brain trauma. CTE has also been found in soldiers exposed to a blast or a concussive injury, in both cases resulting in characteristic degeneration of brain tissue and the accumulation of tau protein. CTE may develop from sub-concussive impacts, meaning that the diffuse axonal injuries involved were insufficient to result in a concussion, but nonetheless accumulate over time. Individuals with CTE may show symptoms of dementia, such as memory loss, aggression, confusion and depression, which may appear years or decades after the trauma.
The majority of conventional headgear, regardless of the sport being played, is composed of a combination of soft compressible material and a hard shell. Upon impact from an object (e.g., another player's helmet, body part, or a ball/puck), the soft material of the headgear may compress and absorb some of the energy, while the hard material may spread the impact energy out over the surface of the headgear shell and effectively increase the surface area. Such conventional headgear may be effective at protecting against types of injuries caused by localized tissue damage, thereby reducing the number of cuts, broken bones, bruises, skull fractures, etc.
Unfortunately, conventional headgear is not designed to prevent concussions or CTE. In fact, in 1974 the National Operating Committee on Standards for Athletic Equipment (NOCSAE) defined their set of safety standards for helmets/headgear using a “linear drop test.” Such a test is involves fitting a headform with the helmet and dropping the headform onto an anvil from various orientations. The standard developed in 1974 has remained largely unchanged to date. While there is evidence to believe that helmets designed to according to the NOSCAE safety standard prevents the likelihood of a skull fracture, there is little reason to believe conventional headgear is effective at reducing incidences of concussions or CTE.
Therefore, there is a continued need for improved headgear to reduce an incident of a concussion or reduce the likelihood of developing CTE.